X-ray production is traditionally accomplished through the process of colliding an electron beam of charged particles with a target assembly. X-rays are produced from the interaction of the electron beam and atoms within the target assembly. This is accomplished through the use of target assemblies with high atomic numbers. The electrons are usually produced by a hot filament and are accelerated to the target by a large potential. When they strike the target, they are deflected by the target atoms and this generates the x-rays. This is the principal mechanism for the production of x-rays for use in computed tomography systems.
Unfortunately, in many target assemblies utilized in CT systems a large percentage of the electron energy is dissipated as heat. This generates a multitude of problems. Many existing target assemblies may not generate sufficient x-rays without a significant introduction of electron energy. Increase in electron energy in these designs, however, further increases the energy that must be dissipated as heat. This, in turn, creates a danger to the target surface and is known to melt the target surface if not carefully controlled. Heat dissipation in combination with adequate x-ray production can also place difficulties on the reduction of x-ray focal spot dimensions.
Flat-panel transmission x-ray source designs are presently utilized to generate multiple focal spots on the imaging object simultaneously. The use of such multiple focal spot imaging can improve volumetric CT imaging. Existing multiple focal spot designs, however, often suffer from the aforementioned concerns regarding the difficulty of generating sufficient x-rays in order to generate good CT images without melting the target assembly.
It would, therefore, be highly desirable to have an improved target assembly capable of generating an increase number of x-rays without melting the target assembly. It would additionally be highly desirable to have an improved target assembly that could provide reduced focal spot dimensions. Finally it would be highly desirable to have an improved target assembly suitable for use in multi-focal spot imaging such that volumetric CT imaging and perfusion studies can be improved.